Myo-Inositol appears to be universally distributed in nature and scyllo-inositol is found to accompany myo- whenever sufficiently sensitive methods have been used. While myo-inositol has a clearly defined function as a percursor of the phosphoinositides it is widely held that it has other important functions also. Scyllo-Inositol has no known function. These two inositols are found in high concentration in nervous tissue. The objectives of the proposed research are to determine the sources of scyllo-inositol in mammals, and its distribution, especially relative to myo-inositol at the cellular level. To this end we are studying the enzymes which reduce myo-inosose-2 to myo- and scyllo-inositol in mammals and employing mass fragmentography (multiple ion detection, MID) to measure myo-inositol in 5-50 ng dry weight brain tissue slices. We hope to begin the measurement of scyllo-inositol in the larger of these tissues in the next year. We are using the MID method for measuring myo-inositol to determine its distribution at the cellular level (large single cells in the CNS, to small populations of cells). We are also studying the affinity chromatography of L-myo-inositol-l-P synthase in order to sufficiently purify it to enable us to prepare fluorescent antibody so as to attempt the localization of this in tissues, especially the CNS. BIBLIOGRAPHIC REFERENCES: D.E. Kiely and W.R. Sherman, "A Chemical Model for the Cyclization Step in the Biosynthesis of L-myo-Inositol 1-Phosphate", J. Amer. Chem. Soc. (1975). J. Wiecko and W.R. Sherman, "Mass Spectral Study of Alkaneboronates of Sugar Phosphates. Evidence of Interaction Between the Phosphate Group and Boron Under Electron Impact Conditions", Org. Mass Spectrom. (1975).